The broad process of forming an agglomerated product, as a pellet or a ball, from a suspension of solid material or materials in a finely divided form has long been known and certain specific processes utilizing the basic concept are set forth in a variety of United States and other patents. Examples of these patents are those to Puddington and Farnand U.S. Pat. No. 3,268,071, Sirianni and Puddington U.S. Pat. No. 3,368,004 and Capes et al U.S. Pat. No. 3,471,267. Briefly, all three of these patents refer to a procedure wherein the powders are suspended in a first liquid which is lyophobic to said powders, a second or bridging liquid is then added thereto which is chosen or treated so as to be lyophilic to at least certain of said powders and the system is then agitated. This forms the material which is lyophilic to the bridging liquid into a plurality of agglomerates whose size and shape depend on the details of said procedure as same are set forth at length in said patents and to which reference is invited. These procedures may be and are used both for the separation of one of a mixture of solids from such mixture and such is the main purpose of the above-mentioned Puddington U.S. Pat. No. 3,268,071, or they may be and are used where the formation of an agglomerated product is the objective itself of the agglomeration procedure and such is the principal purpose of the other two patents above-named.
The processes above-described are highly successful within certain limits which are reasonably well understood by those skilled in the art but workers in this field have been unable by following the processes of said patent to obtain the range of properties which are desirable to make such processes of broad industrial applicability. For example, in making balls by agglomeration processes it is often desirable to have said balls exhibit a substantial degree of hardness and/or strength, such as if said balls are to be used as bearing balls. This cannot be obtained according to the processes of the above-mentioned patents excepting by supplemental procedures such as adding binders or by sintering. However, while this provides hardness, these procedures often introduce other problems such as undesirably raising density, decreasing porosity or in the case of the addition of binders introducing essentially what is a contaminant. This latter can be undesirable where the agglomerates are to be used as catalytic pellets or solid fuel particles.
Thus it is desirable to provide a method employing generally the agglomerating techniques of the above-mentioned patents but wherein said techniques are modified and extended to make possible a wider range of control and/or selectability of the properties of the resulting product than is possible by presently known techniques.
Accordingly, the objects of the invention include the following:
1. To provide a process for agglomerating finely divided solid materials which will produce agglomerates of wider range and selectivity of properties than was formerly possible, such as hardness, mechanical strength, solubility, bulk density, surface area, chemical activity.
2. To provide a process, as aforesaid, which is an improvement over the procedures disclosed in the three above-mentioned patents.
3. To provide a process for agglomerating finely divided solid materials which while basically employing the hydrophobic-hydrophilic forces relied upon by the above-mentioned patents, additionally modifies the materials involved therein by one or more selectable chemical reactions whereby to supplement the effects of the hydrophobic-hydrophilic procedures and obtain thereby a much wider range of and better control over, the properties of the final product.
4. To provide a process for agglomerating finely divided solid materials which will be extendible to situations (referring primarily to materials and suspendant liquids) which do not respond at all to hydrophobic-hydrophilic processes.
5. To provide a process, as aforesaid, which, for many cases, will not add material expense over the procedures disclosed in any or all of the three above-mentioned patents.
6. To provide a process, as aforesaid, which can be carried out with relatively simple equipment, including equipment essentially similar to that set forth in the above-mentioned patent to Capes et al U.S. Pat. No. 3,471,267.
7. To provide a process, as aforesaid, which is applicable to a wide range of powdered materials and which can be carried out with a wide range of treating materials.
8. To provide a process, as aforesaid, whose details may be readily modified in a given case according to the particulars of the starting material used and the precise nature of the end products desired.
Other objects and purposes of the invention will be apparent to those skilled in the art upon reading the following disclosure and inspecting the accompanying drawings.